<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>cors解决跨域</h1>
    <button id="btn">提交请求</button>
    <script>
        const btn = document.querySelector('#btn')
        btn.onclick = function(){
            const xhr = new XMLHttpRequest()
            xhr.open('get','http://127.0.0.1:4545/userInfo',true)
            xhr.send()
            xhr.onreadystatechange=function(){
                if(xhr.readyState === 4 && xhr.status >= 200 && xhr.status <= 299 ){
                   const result = JSON.parse(xhr.responseText)
                   console.log(result);
                }
            }
        }
       
    </script>
</body>
</html>